protected virtual member function
basic_streambuf* setbuf (char_type* s, streamsize n);
Virtual function called by the public member function pubsetbuf to influence the object in a way that is dependent on the library implementation.
If both arguments are zero, the call is guaranteed to have no effect on the basic_stringbuf object.
- s, n
If both are zero, no effect.
Member type char_type is the type of the characters in the stream buffer (the first class template parameter).
streamsize is a signed integral type.
If both arguments are zero, it introduces no data races.
Basic guarantee: if an exception is thrown, the object is in a valid state.